Early use of cables to carry and propel conveyor belts is shown in U.S. Pat. No. 826,312 wherein the belt is releasably attached to the cables in the working run and is detached from the cables at the ends of the working run. In this prior construction, the belt is carried on end idler pulleys independently of the cables which are carried by a pair of sheaves positioned beyond the end idler pulleys. This positioning of the cable sheaves at the end of the conveyor complicates unloading or discharge from the head end of the conveyor. Later belt conveyors having conveying belts supported on cables, but not secured thereto, are shown in Canadian Pat. No. 531,393; West German Pat. No. 2,153,389 and U.S. Pat. Nos. 843,018; 1,970,842; 2,656,035; 2,751,065 and 3,381,799. The use of carrying straps to suspend a conveyor belt between two support cables, wherein the straps are secured to both the cables and the belt, is shown in German Pat. No. 226,080 issued Sept. 26, 1910, and in U.S. Pat. No. 1,530,707.
In the sling belt conveyor of U.S. Pat. No. 2,925,903, spring type hangers are connected via hinges to opposite edges of a conveyor belt and fastened to suspension drive cables. The spring type hangers present potential resonance problems and a special belt and/or belt modifications are required. It will also be noted the direction of the load transmitted by the support cable to the intermediate support pulley does not pass through the plane of the support pulley.